A follow-up study on the development of the factors that have effects upon gaining ball speed in kicking motion

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The purpose of this study is to investigate the relative development of the factors that have effects upon gaining ball speed in kicking motions under two different ballconditions : stationary and tee-up.The results are summarized as follows.1.Ball speed was increased remarkably with age and showed high correlation between swing speed.2. Other factors that showed remarkable change were swing speed, angle of the kicked ball in stationary ball, maximal angle of upper limb of pivot leg side in kicking angle of upper limb of kicking leg side at impact, range of knee angle and the position of ball contact.3.In infancy, positioning his waist behind the ball and leaning backward make it easier to extend the knees and this movement is one of the characteristic of ball kicking. Dynamic movement of kicking leg and upper limb of pivot leg side would be effective indexes of kicking motion in infancy.4. At the stage of 9 to 11 years of age, angle of the kicked ball in stationary ball and the position of ball contact progresed remarkably. It suggests thet they can kick by instep and the technical factor has higher effect on gaining ball speed.5.At the stage of 10 to 12 years of age, the tibialis anterior showed strong discharge before and after the ball contact. It suggests that muscular strength also effects on gaining ball speed.